Jim Mattis, who served as Defense Secretary in the Trump administration, is on tour plugging his new book, “Call Sign Chaos,” but those expecting the former general to trash President Donald Trump may be set for disappointment.

In an appearance Tuesday on “Fox & Friends,” Mattis discussed the military’s role in the face of storms like Hurricane Dorian, which is sitting just off the coast of Florida, before getting into his book, beginning with the name.

Mattis explained that “Chaos” was a tongue-in-cheek acronym from his early days in the U.S. Marine Corps, as one of his operations officer decreed: “Colonel Has Another Outstanding Suggestion.”

After stating that his book is about leadership and allies, and how to set the vision as a leader, Fox News co-host Steve Doocy was prompted to ask Mattis about his tenure with President Donald Trump.

“Do you talk about working as defense secretary for Donald Trump in the book,” he asked.

Pointing out that he began writing the book with his coauthor, Bing West, in 2013, Mattis replied that he did not talk about that experience in any detail, focusing more on lessons learned throughout his career that he felt compelled to pass on.

Pressing, Doocy said that “a lot of people would like to hear about it. From where we sat it looked like a tense relationship.”

“No, it wasn’t a tense relationship,” Mattis corrected him. “The president is a forthright man and so am I. I would meet with him weekly. There was nothing going on that I wasn’t open with him about. That’s the way I deal with my boss anywhere I have ever been.”

“Because he is the boss, right?” Doocy said.

“He was elected by the American people,” Mattis replied.

Co-host Brian Kilmeade asked the former Defense secretary about disagreeing on pulling troops out of Syria.

“The report was one of the things you said is, ‘Have your next Secretary of Defense be the one to lose to ISIS.’”

But Mattis wasn’t biting.

“I maintain confidentiality, Brian, when I talk with the President. I would just tell you that —” he began.

“But you don’t back away from that assessment, right?” Kilmeade interjected.

“Well, I was asked to serve. I come from — I was raised by the greatest generation.”

Doocy jumped in to say that Mattis came out of retirement to serve under Trump.

“I did. I was enjoying life,” he said. “But when you are asked to serve, Republican or Democrat, don’t start wringing your hands and asking what to do. Just roll up your sleeves if you are prepared, go to work and do your best. It’s very, very simple.”

After discussing his career somewhat, Doocy brought up the general’s well know nickname, “Mad Dog.”

“I don’t know where it came from,” he replied. “We were reading the newspaper one day outside Fallujah during a battle that was very rough — the Marines were fighting like the dickens and in the lull we got newspapers and one of them said, ‘Where did this come from?’ … and he read the ‘Mad Dog’ thing for the first time and said we all know your call sign is ‘Chaos.'”

“It must’ve been a slow news day,” Mattis said, adding that “it didn’t sit well with me. Never has.”